The present invention concerns a Peltier effect device aiming in particular at detecting a condensation risk on a surface being in contact with a wet air volume.
Devices which detect the dew-point temperature and the ambient air relative humidity are already known.
The U.S. Pat. No. 4,677,416 document describes a device with a substrate on the upper face of which two semiconducting PbTe bands, alternately of N-type and P-type, are mainly formed. The bands extend between a peripheral zone and a central zone of the upper face of the substrate, and are connected in series by N-P and P-N type junctions and constitutes a circuit alternately formed of N-type bands and P-type bands. All N-P type junctions are situated in the central zone of the substrate, and all P-N type junctions are situated in the peripheral zone of the substrate.
In such a device, when current passes in the series circuit, the central zone of the substrate is cooled down by the Peltier effect. A quantity of heat is absorbed by the junctions present in the central zone of the substrate and released with an approximate amount equivalent to the Joule effect, by the junctions present in the peripheral zone of the substrate.
However, the efficiency of this device may prove to be insufficient because the peripheral junctions are situated on the same face of the substrate as the detection zone, such that while the detection zone is cooled down by the Peltier effect, it may receive a part of the thermal energy released by the peripheral junctions.
Besides, this thermal energy is mainly transmitted by conduction in the thickness of the substrate before being dissipated.
Such inconveniences do not really matter in case of a dew-point temperature measurement, but when a condensation risk has to be detected, for instance by implementing the process described in the unpublished patent application No. 93 02099 of the requesting party, it is better to have a Peltier effect device which is able to quickly dissipate the thermal energy released by the junctions situated outside the detection zone, such that the detection zone is not subject to the influence of such dissipation.